Apparatus for wrapping palletized commodities in plastic film

ABSTRACT

A pallet base stacked with commodities for wrapping is positioned on a horizontal platform, whereupon the wrapping operation is effected by an L-profile beam carrying a roll of plastic film and rotatable about a vertical axis in such a way as to circle the platform and wind the film around the pallet; to advantage, the horizontal member of the beam lies below the uncoiling roll of film, passing between the platform and a horizontal bed afforded by the stationary frame of the apparatus, such that with the L-beam set in rotation about the main axis a low center of inertia is achieved.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for wrapping palletizedstacks of commodities in a plastic film material.

There are currently numerous machines of the type in question availablefor purchase (typically as disclosed in Italian patent 1 179 310),consisting generally in a load-bearing frame of gantry typeconstruction, and a beam of upturned `L` profile suspended rotatablyfrom the center of the frame by the horizontal member of the `L` and setin motion by a drive system. The vertical member of the `L` carries astation serving to support a roll of the plastic wrapping film; as arule this same station is also capable of a controlled traversingmovement on the vertical member of the beam, such that the stackedcommodities can be enveloped to their full height.

The palletized stacks of commodities for wrapping are positioned at thecenter of the apparatus, or rather the center of the gantry, either by apallet lift truck (in the case of more simple equipment), or by means ofa permanently installed horizontal conveyor running at floor leveldirectly beneath the gantry; once the pallet is at a standstill in therequired position, a restraint device will be activated in such a way asto descend and stabilize the entire pallet load by engaging the top faceof the stack of commodities. Thereupon, the free end of the film issecured to the pallet base or held fast by means of a gripper mechanism,and the drive system is activated: the upturned `L` beam begins circlingthe pallet, and the stacked commodities are enveloped gradually by theuncoiling film. Where the width of the film is less than the height ofthe stacked commodities (as will normally be the case), the roll of filmnaturally must be made to ascend and descend on the vertical member ofthe beam to ensure that the commodities are enveloped completely fromtop to bottom. In most instances the plastic film is stretched duringthe wrapping operation (by applying a braking action to the roll) to theends of achieving a certain saving on the cost of the wrapping materialutilized, and of increasing the tension of the wrapping in order toenhance its ultimate tightness around the pallet, especially where thecommodities are stacked high. The main drawbacks besetting suchapparatus derive for the most part from the significant bulkiness of thegantry frame, which has to carry the `L` beam and its drive system,together with the relative transmission components. As a directconsequence, the entire apparatus is rendered especially heavy, notleast by reason of the fact that the center of the masses in rotationlies high up in the frame, demanding suitably proportioned reactionelements to offset the forces generated in operation. A furtherdrawback, stemming from the first, is the need to maintain a lowwrapping speed precisely in order to limit the mechanical stressesgenerated in rotation.

Accordingly, the object of the present invention is to overcome thedrawbacks briefly outlined above, by providing an apparatus for wrappingpalletized stacks of commodities such as will ensure a swift, precisewrapping action and faster operation per unit of mass, while featuringcompact dimensions and advantages of economy.

SUMMARY OF THE INVENTION

The stated object is realized in an apparatus for wrapping palletsaccording to the invention, which is of the type comprising a frame, andsupported by the frame, a beam of `L` profile anchored rotatably to theframe and set in motion by a drive system, of which the vertical membersupports a roll of wrapping material rotatable about its own verticalaxis and invested with controlled axial movement by a relative drive insuch a way as to ascend and descend on the vertical member; also ahorizontal platform on which to stand the pallet, and gripping means,positioned adjacent to the roll, by which the material is secured to thepallet at its free end before the start of the wrapping operation andcut through on completion of the operation. Advantageously, in theapparatus disclosed, the `L` profile beam is disposed with thehorizontal member positioned beneath the roll of wrapping material,extending between the base of the frame and the platform which supportsthe pallet, and is anchored in rotation at a point low down in theapparatus, coinciding with the axis of rotation of the beam.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in detail, by way of example, withthe aid of the accompanying drawings, in which:

FIG. 1 shows the wrapping apparatus according to the invention in a sideelevation, with certain parts cut away better to reveal others, andcertain shown in section;

FIG. 2 is an exploded illustration of the drive transmission arrangementutilized in the apparatus according to the invention;

FIG. 3 is a top view of the apparatus, and more especially of the drivetransmission of FIG. 2, in which certain parts are cut away better toreveal others.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the accompanying drawings, a wrapping apparatusaccording to the invention (see FIG. 1 in particular) comprises a frame,denoted 1, and a beam 2 of `L` profile consisting essentially in avertical member 3 and a horizontal member 11, mounted rotatably to theframe 1 and set in motion by drive means, for example a geared motor 31;the vertical member 3 of the beam serves to support a roll 4 of stretchplastic film 5, which is able to rotate about its own vertical axis(denoted X) and capable also of controlled sliding movement, in avertical direction, produced by means 30 consisting in a carriagebracket 32 disposed transversely in relation to the vertical member 3and furnished with wheels 33 running on a vertical track 34; thecarriage 32 is set in motion by a drive unit 35 positioned at the baseof the vertical member 3, and a chain 36 connected to the carriageitself. The frame 1 also supports a horizontal platform 6 on which tostand the pallet 7 with its stack of commodities 8; in the embodimentillustrated by way of example, the platform coincides with a rollertable 24 carrying gripping means 10 on the side nearer to the roll 4, bywhich the film 5 is made fast at its free end to the commodities 8 asthe wrapping operation commences, and cut through once the operation hasbeen completed.

Advantageously, the horizontal member 11 of the `L` beam 2 is positionedbeneath the roll 4, extending between a horizontal bed 1a afforded bythe frame 1 and the platform 6 which supports the pallet 7, andvirtually anchored pivotably at a point P coinciding low down in theapparatus with a vertical axis V about which the beam 2 is caused torotate in a first direction denoted S1 in FIG. 2. Likewise in FIG. 2, itwill be seen that the endmost portion 11a of the horizontal member 11lying remote from the vertical member and beneath the platform 6 issubstantially annular in embodiment.

12 denotes means associated with and serving to set the platform 6 inrotation about the aforementioned axis V, in a direction S2 (FIG. 2)opposite to the first direction S1. The means 12 in question are to allintents and purposes drive transmission means, interposed between theframe 1 and the platform 6, by which both the horizontal member 11 andthe platform itself are invested with motion in such a manner as toallow of rotating the beam 2 in the first direction S1 and at the sametime rotating the platform 6, or at least the part of the roller table24 occupied by the pallet 7, in the opposite direction S2 (the twodirections of rotation are clearly discernible from FIGS. 2 and 3).

More exactly, such drive transmission means 12 (see FIGS. 2 and 3 inparticular) include a first driving gear wheel 13 keyed coaxially to theshaft of the aforementioned geared motor 31, which is mounted to theframe 1; this first gear wheel 13 meshes with an internally andexternally toothed first ring gear 14 rigidly associated with a firstbearing 15 located between the annular end portion 11a of the horizontalmember 11 and the frame 1, such that the horizontal member 11 is able torotate in the first direction S1.

The internal teeth of the first ring gear 14 mesh in turn with thebottom gear wheel 16a of a double idler 16, freely rotatable andsupported from the frame 1 by means of a bracket 37, of which the topgear wheel 16b meshes in a plane above the plane of rotation of thehorizontal member 11 with a second idle gear 17, also freely rotatableand supported by the bracket 37. The second idle gear 17 meshes in turnwith a second ring gear 18 similar to the first but with internal teethonly and associated rigidly with a second bearing 19, located betweenthe platform 6 and the horizontal member 11, which allows the platform 6to rotate in the direction S2 opposite to that of the horizontal member11. 20 and 21 denote rotary type power contactors or couplings(indicated schematically in FIG. 1, being conventional in embodiment)associated centrally with the first and the second bearing 15 and 19,respectively, and brought into dynamic operation during rotation of thehorizontal member 11 and of the platform 6. The second bearing 19 isseated on a ring 22 which serves also to distance the bearing from thehorizontal member 11.

9 denotes a restraint mechanism associated with the `L` profile beam 2and positioned above the pallet, of which the purpose is to immobilizethe stack of commodities 8 in relation to the platform 6 for theduration of the wrapping operation; more exactly, the restraintmechanism 9 is carried by a second horizontal member 23 disposedtransversely to and extending from the top end of the vertical member 2of the beam, and consists in a plate 40 associated with a central rod 41accommodated axially and slidably, and adjustable for position throughthe agency of spring means 42, by a sleeve 43 attached to the secondhorizontal member 23.

With an apparatus thus embodied, the operation of wrapping palletizedstacks of commodities 8 occurs in the following manner: a pallet 7stacked with commodities 8 is set down on or conveyed onto the platform6, whereupon the free end of the film 5 is drawn from the roll 4 andanchored by the gripping means 10, while the restraint mechanism 9 iscaused to descend and engage the upward-facing side of the commodities8; thereafter, the geared motor 31 is activated to rotate the first gearwheel 13 in the direction denoted F in FIGS. 2 and 3, the result ofwhich is that the first ring gear 14 rotates in the first direction S1on the relative bearing 15, and with it the horizontal member 11. Thefirst ring gear 14 sets both the bottom wheel 16a and the top wheel 16bof the double idler 16 in rotation, and in the same direction S1. Thetop wheel 16b in its turn rotates the second idler 17 in the oppositedirection F1 to that of its own rotation, with the result that thesecond ring gear 18 is also set in rotation, enabled by the bearing 19to move in the direction S2 opposite to the direction S1 of the firstring gear 14, and with it, the platform 6. From this point, wrapping ofthe pallet 7 proceeds continuously as the horizontal member 11 and theplatform 6 rotate in mutually opposite directions (clockwise andanticlockwise, or viceversa), and the roll 4 of material 5 ascends anddescends on the vertical member 3 of the beam 2 (arrow F3) to ensurethat the stacked commodities 8 are enveloped completely from top tobottom.

An apparatus thus embodied is able to wrap pallets swiftly and securely,employing a simple and safe structure of compact dimensions thatrequires the minimum of space in which to operate; and with the centerof mass of the beam situated low in relation to the frame, furthermore,it becomes possible to dispense with the cumbersome and costlystabilizing structures necessitated by prior art embodiments of the typementioned at the outset, and thus achieve a notable reduction in thecost of the apparatus as a whole.

What is claimed is:
 1. An apparatus for wrapping palletized stacks ofcommodities in plastic film material, comprising:a frame, affording ahorizontal bed; a horizontal platform, mounted on said frame, on whichto stand a single pallet base stacked with commodities; a beamsubstantially of `L` profile exhibiting a horizontal member and avertical member, supported by and anchored rotatably to the frame andset in motion by drive means, of which the vertical member carries aroll of plastic film material rotatable about its own vertical axis andinvested with controlled axial movement by further drive means in such away as to ascend and descend on the vertical member, and the horizontalmember is positioned beneath the roll, extending between the horizontalbed and the platform, and anchored in rotation at a point low down inthe apparatus, coinciding with the axis about which the beam is causedto rotate in a first direction; gripping means, positioned adjacent tothe roll, by which the film is secured to the commodities at its freeend before the start of the wrapping operation and cut on completion ofthe operation; a drive transmission means, interposed between the frameand the platform and associated both with the platform and with thehorizontal member of the `L` profile beam, said drive transmission meanscausing said beam to rotate in the first direction for generating thewrapping action, and said drive transmission means causing at least thepart of the platform occupied by the pallet to rotate simultaneously inthe opposite second direction; a single motor for driving said drivetransmission means;wherein the drive transmission means comprises: afirst driving gear wheel associated with drive means mounted to theframe by which the horizontal member is caused to rotate, in mesh withan internally and externally toothed first ring gear rigidly associatedwith the top face of a first bearing located between the horizontalmember and the frame and allowing the horizontal member to rotate in thefirst direction; a double idle gear freely rotatable and mounted to theframe, of which a bottom gear wheel meshes with the internal teeth ofthe first ring gear and a top gear wheel meshes in a plane above theplane of rotation of the horizontal member with a second idle gear, alsofreely rotatable and mounted to the frame; an internally toothed secondring gear associated rigidly with a second bearing, said second ringgear meshing with said second idle gear, said second ring gear beinglocated between the platform and the horizontal member, on which theplatform is able to rotate in the direction opposite to that of thehorizontal member.
 2. An apparatus as in claim 1, wherein the drivetransmission means comprises first and second bearings which areassociated each with a relative centrally positioned rotary contactor orcoupling of which the action accompanies rotation of the horizontalmember and of the platform respectively, and the upper second bearing isseated on a ring serving also to distance it from the horizontal member.3. An apparatus as in claim 1, further comprising a restraint mechanismassociated with the `L` profile beam, occupying a position above theplatform at the free top end of the vertical member and carried by asecond horizontal member disposed transversely to the vertical member,the purpose of which is to stabilize the stacked commodities for theduration of the wrapping operation.
 4. An apparatus as in claim 1,wherein the part of the horizontal member interposed between theplatform and the frame is of annular embodiment.
 5. An apparatus as inclaim 1, wherein the platform consists in at least one section of aroller table with which the gripping means are associated on one side.6. An apparatus for wrapping a palletized load with a sheet material,the apparatus comprising:a platform which carries the palletized load; abeam carrying a roll of wrapping plastic film, said beam being locatedat a predetermined distance from said platform; and, a means,operatively connected to said platform and to said beam, for creating arelative rotation between the palletized load and the roll of wrappingplastic film, said means comprising: a motor, a first linkage forconnecting said motor to said beam, a second linkage for connecting saidmotor to said platform, wherein said motor drives said first linkage soas to rotate said beam in a first direction and simultaneously drivessaid second linkage to rotate said platform in a seconddirection;wherein said first linkage comprises: a first gear ringsecured to said beam; a gear wheel secured to a shaft of said motor,said gear wheel being in eared connection with said first gearring;wherein said second linkage comprises: a bracket having first andsecond ends, said first end being secured to a support surface; a gearassembly secured to said second end of said bracket, said gear assemblybeing in geared connection with said first gear ring; and, a second gearring secured to said platform, said second gear ring being in gearedconnection with said gear assembly.
 7. The apparatus of claim 6 furthercomprising a gripping means for securing an end of said wrapping plasticfilm before the start of the wrapping operation.
 8. The apparatus ofclaim 6 further comprising a restraint means located above thepalletized load for stabilizing the palletized load.
 9. The apparatus ofclaim 8 further comprising a connecting arm for connecting saidrestraint means to said beam.
 10. An apparatus for wrapping a palletizedload with a sheet material, the apparatus comprising:a platform whichcarries the palletized load; a beam carrying a roll of wrapping plasticfilm, said beam being located at a predetermined distance from saidplatform, said beam comprising: a vertical arm, and a first horizontalarm, said roll of plastic film being suspended from said vertical armand said first horizontal arm extending to said platform; and, amechanism, operatively connected to said platform and to said beam, forrotating said platform and hence the palletized load in a firstdirection and for rotating said beam and the roll of wrapping plasticfilm in a second and opposite direction, said mechanism comprising: amotor, a first linkage for connecting said motor to said beam, a secondlinkage for connecting said motor to said platform, wherein said motordrives said first linkage so as to rotate said beam in a first directionand simultaneously drives said second linkage to rotate said platform ina second direction;wherein said first linkage comprises: a first gearring secured to said beam; a gear wheel secured to a shaft of saidmotor, said gear wheel being in geared connection with said first gearring;wherein said second linkage comprises: a bracket having first andsecond ends, said first end being secured to a support surface; a gearassembly secured to said second end of said bracket, said gear assemblybeing in geared connection with said first gear ring; and, a second gearring secured to said platform, said second gear ring being in gearedconnection with said gear assembly.
 11. The apparatus of claim 10further comprising a carriage bracket for mounting said roll of wrappingfilm on said vertical arm of said beam and further comprising a meansfor raising and lowering said carriage bracket on said vertical arm. 12.The apparatus of claim 10 further comprising a gripping means forsecuring an end of said wrapping plastic film before the start of thewrapping operation.
 13. The apparatus of claim 10 further comprising arestraint means located above the palletized load for stabilizing thepalletized load.
 14. The apparatus of claim 13 further comprising asecond horizontal arm having a first end to which said restraint meansis connected and having a second end connected to said vertical arm ofsaid beam.